UNISONIC TECHNOLOGIES CO., LTD
UCQ3879
Preliminary
CMOS IC
LOW COST POWER-SAVING
MODE PWM CONTROLLER FOR
FLYBACK CONVERTERS
DESCRIPTION
The UTC UCQ3879 provides a CCM/valley switching mixed
mode operation for better efficiency performance. The UTC
UCQ3879 is a highly integrated current mode PWM control IC with
high voltage start up, optimized for high performance, low standby
power consumption and cost effective offline flyback converter
applications. At no load condition, the IC operates in power-saving
mode for lower standby power, decreasing frequency for Higher
conversion efficiency at light load condition.
SOP-8
The UTC UCQ3879 contains protection with automatic recovery
including OLP (over load protection), OCP (cycle-by-cycle current
limiting), and UVLO (VDD over voltage clamp and under voltage
lockout). It also provides the protections including OTP (over
temperature protection), BNO(AC Brown Out protection) , LNO(AC
Over voltage protection), OVP (VCC or DC output over voltage
protection) with automatic recovery. To protect the power MOSFET,
Gate-drive output is fixed up to 16V max.
The internal slope compensation improves system stability at high
PWM duty cycle output. Leading-edge blanking on current sense
input removes the signal glitch, which offering minima external
component count in the design. Excellent EMI performance is
achieved with UTC proprietary frequency hopping technique
(ZL201020615247.1) together with soft driver control. Audio noise is
eliminated due to switch frequency more than 20kHz during
operation.
UTC UCQ3879 is packaged by using tiny SOP-8 package. It has
such applications as: battery charger, power adaptor, set-top box
power supplies, ink jet printers, open-frame SMPS.
FEATURES
* Built in high voltage(680V) startup
* Built in x-cap discharge function
* Proprietary frequency hopping for Improved EMI performance
* Cycle-by-cycle current limiting
* CCM/Valley Switching Operation
* Fixed switch frequency 60~70kHz
* Dynamic peak current limiting for constant output power
* Built-in synchronized slope compensation
* Gate output voltage clamped at 16V
* Adjustable DC output OVP
* OLP/VCC OVP/OTP/BNO/LNO (automatic recovery)
* Internal Soft Start
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